Computing at School* are writing a user guide for the RasPi and this will be available by April. It will include a section on programming in Python so you may be able to use this . It will be targeted at school age kids. There will be projects in there, nothing definite yet but I think that the project based club will be the way to go and you have some good ideas there already. I'll be running a similar club myself so will give this some thought (Ok, I'll be pinching some of your ideas
The VERY first thing I would do with them is to get them to personalise their Pi - name on the start screen, welcome message, set up icons like you would do with a phone etc - make it their personal machine.
*Disclaimer: I'm a member of CAS and helping write the guide